One vertex per element, one color per generator, with an edge from x to x·s.
(2,5)(3,7)(10,12)(14,16)(17,18)(19,23)(20,22)(21,24)(25,26)(27,32)(28,29)(30,31)(33,37)(34,40)(35,39)(36,38) involution — undirected(2,5)(6,8)(11,15)(14,16)(17,19,22,21)(18,23,20,24)(26,31)(28,36)(32,39)(33,40)(1,2)(3,6)(4,5)(7,8)(9,10,13,12)(11,14,15,16)(17,19,22,21)(18,24,20,23)(25,27)(26,32)(28,33)(29,37)(30,35)(31,39)(34,38)(36,40)(1,2)(3,6)(4,5)(7,8)(9,11,13,15)(10,14,12,16)(17,20,22,18)(19,23,21,24)(25,28,30,36)(26,29,31,38)(27,33,35,40)(32,37,39,34)(1,3)(2,6)(4,7)(5,8)(9,12,13,10)(11,16,15,14)(17,21,22,19)(18,23,20,24)(25,29)(26,28)(27,34)(30,38)(31,36)(32,40)(33,39)(35,37)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.